Abstract: The two-component transporter YvdSR expressed by the two-component gene YvdSR from Bacillus subtilis strain 168 was functionally identified. It was concluded that YvdSR had the function of transporting Na⁺/Li⁺. In order to explore the ion transport mechanism of Yvd SR, the homologous sequence alignment of the two components was carried out, and completely conserved acidic amino acid residues were screened from each component and site-directed mutagenesis of amino acid residues was carried out. The E13 shared by YvdS and YvdR was completely conserved in the homologues and lost Na⁺（Li⁺）/H⁺ reverse transport activity after mutation to alanine, indicating that the E13 of both components was indispensable for protein function. In addition, the E13A of YvdS could restore high levels of Na⁺（Li⁺）/H⁺ reverse transport activity after reverse mutation, while the E13A of YvdR still lost Na⁺（Li⁺）/H⁺ reverse transport activity after reverse mutation, indicating that YvdS and YvdR had different functions in Na⁺（Li⁺）/H⁺ reverse transport.